I have a mag 7 in my sump and it is not what I call loud. Loudest part would be if it is sitting on glass or acrylic and is vibrating. Put a filter pad under in and see if it helps. Mine sits in my acrylic sump with no noise.
If that does not do it, you can take it apart and see if something is caught in the impeller chamber.
*180 gal Display, 100 gal basement sump, 33 gal refugium, 3x250 MH, 2x160 VHO actinics, zoos, some softies, LPS & lots of acros and other SPS.
*100 gal prop tank plumbed into main system w/ 2x96 PC lights and 1x150 MH,